Elusive orcas seen launching prey into air as unique diet is revealed, study says

Off the coast of Chile live a mysterious population of orcas that have long eluded scientists.

But now, following years of dogged data collection, researchers have managed to shed light onto one key aspect of the apex predator’s lives: their diet.

For the first time, the orcas have been observed hunting, eating and sharing dusky dolphins, a small dolphin species found in the southern hemisphere, according to a study published Sept. 25 in the journal Frontiers of Marine Science.

Scientists at various institutions in Chile took part in boat surveys in the Humboldt Current System — a cold ocean current that flows northward along the coast of South America — in order to draw their conclusions. When they spotted orcas, they deployed drones in order to capture footage.

They also relied on observations from local anglers and whale watchers, which were made between 2010 and 2021.

The process was a grueling one, researchers said.

“Studying orcas in their natural environment is very challenging as they are marine top predators, traveling long distances and living offshore, which makes observation difficult,” Ana García Cegarra, one of the study authors, said in a journal news release.

Hunting and sharing dusky dolphins

Orcas are known to have an extremely varied diet, with different populations having a preference for unique species of prey, including seals, turtles, seabirds and fish.

Through their observations, scientists recorded evidence of the Chilean orcas hunting dusky dolphins — which killer whales in the region had never before been documented eating.

The orcas were seen hunting the dolphins on multiple occasions, sometimes in pairs, according to the study.

On one occasion, a female was observed dramatically “throwing (a) dusky dolphin into the air.” A photo of the incident shows the prey upside-down and fully above the water.

The scientists also documented the orcas eating the dolphins, often sharing them with others.

In one instance, an older orca was seen sharing the spoils of a hunt with a calf.

“We observed how the adult female (presumably the calf’s mother) held the dusky dolphin with her mouth, allowing to the calf to bite off smaller pieces of meat,” according to the study.

Food sharing has been documented among multiple groups of orcas — either as a result of cooperative hunting or to feed relatives.

With the Chilean orcas, it’s believed that they were splitting up the dolphins with their kin.

While further research is needed, the findings can help advance conservation efforts.

“Understanding their role in the marine environment is crucial for the conservation of this poorly-known species in the Humboldt Current,” García Cegarra said.

This story was originally published September 27, 2024 at 8:30 AM with the headline "Elusive orcas seen launching prey into air as unique diet is revealed, study says."